Noticing a black or dark toenail can be alarming. Sometimes it’s harmless. Other times, it needs medical attention. The key is understanding the cause.
Here’s what a black toenail could mean — and what you should do next.
1️⃣ Bruised Toenail (Most Common Cause)
The most frequent reason is a bruise under the nail, known as a subungual hematoma. It happens when blood collects beneath the nail after:
• Dropping something on your toe
• Tight shoes
• Long-distance running
• Repeated pressure or trauma
The nail may look dark red, purple, or black.
What to do:
If pain is mild, it usually grows out on its own over several months. Keep the nail trimmed and wear comfortable shoes.
If there is severe pressure or pain, a doctor may need to release the trapped blood.
2️⃣ Fungal Infection
A fungal infection can cause thickened, brittle nails that turn yellow, brown, or even dark. The medical name for this condition is Onychomycosis.
Signs include:
• Thick nail
• Crumbling edges
• Bad odor
• Gradual color change
What to do:
Antifungal creams or prescription medications may be needed. Treatment can take several months because toenails grow slowly.
3️⃣ Repeated Friction from Shoes
Athletes often experience black toenails from repeated impact inside tight footwear. Even without a major injury, constant pressure can damage blood vessels under the nail.
What to do:
Switch to properly fitted shoes with enough toe space. Keep nails trimmed short.
4️⃣ Rare but Serious: Skin Cancer
In rare cases, a dark streak or spot under the nail could be a form of skin cancer called Melanoma.
Warning signs:
• Dark streak that doesn’t move as the nail grows
• Pigment spreading to surrounding skin
• No history of injury
• Nail splitting near the dark area
If you notice these signs, see a doctor immediately. Early detection is critical.
🚨 When to See a Doctor
Seek medical advice if:
• Pain is severe
• The nail is lifting or infected
• There was no injury but the nail turned black
• The discoloration is spreading
• You have diabetes or circulation problems
🧴 How to Support Healthy Nails
✔ Keep feet clean and dry
✔ Change socks daily
✔ Wear breathable shoes
✔ Avoid sharing nail tools
✔ Trim nails straight across
❤️ Final Thoughts
Most black toenails are caused by minor injury or pressure and will grow out over time. But if something looks unusual or doesn’t improve, don’t ignore it.
Your feet carry you every day — they deserve attention too.
